1. Field of the Invention
The invention relates in general to devices for protecting buildings from the hazardous effects of exterior explosive blasts and certain natural disasters, and in particular to a protective shield which can be applied to window or other portions of a building for mitigating the effects of exploding or shattered glass and flying debris.
2. Related Art
In exterior explosions and certain natural disasters, a high percentage of injuries and damage are caused by flying debris, particularly from glass and particles from the windows of a building.
Attempts have been made to address this issue. One method is to apply protective film to the window. This reduces the amount of flying glass and debris, but can result in larger pieces of glass and film that still cause injury and damage. Films have a relatively short life cycle, and are subject to UV degradation that causes breakdown in the film and in its adhesives. There are also anchoring problems involved with thicker films and laminates.
Another method involves installing blast curtains at window areas. These blast curtains, however, can be rendered ineffective to potential danger by drawing them open. Furthermore, in most embodiments, extra fabric is stored in a bottom container below the interior side of the window, which is unsightly and collects dust and dirt, requiring periodic cleaning.
Another method involves the use of strong laminated glass at window openings. The strength requirements of the framing around such units are considerable, as the frame must be able to withstand at least as much load as the laminated unit to prevent the unit from becoming detached from the building structure in the event of an explosion. In both new construction and retrofit situations, such framing is very costly.
These and other drawbacks exist in prior methods and apparatuses for blast mitigation.